1. Field of Invention
The invention relates generally to canteens and related personally carried liquid containers and, more specifically, to marine survival equipment.
2. Description of Prior Art
The word "canteen" is normally used to describe a portable flask for carrying water or other liquids. The most familiar type of canteen is the cloth-jacketed metal flask issued to soldiers as a part of their mess kit. Plastic has found wise use in the construction of modern canteen vessels owing to its comparative advantages to metal in the areas of cost, thermal conductivity, and ease of manufacture. Canteens are usually carried by means of a strap, belt, or other personally worn affixing device.
A canteen, when completely filled with liquid, presents little problem to the carrying person. The full canteen responds to normal body movements in a predictable manner, very much like that exhibited by a solid object. When the contents of the canteen have been partially emptied, however, the body movements of the carrying person cause sloshing within the canteen. This sloshing sets up a complex set of forces on the canteen and results in motion similar to that exhibited by a compound pendulum. Unless the partially emptied canteen is tightly strapped to the person, it will exhibit the aforementioned erratic motion, which can be annoying or even physically irritating, depending upon how the canteen is worn.
In the field of marine survival equipment, many inventions have been disclosed which aid in the flotation, insulation, and location of a person who is overboard. Flotation devices include life jackets, life rings, and various types of inflatable air bladders. Since a person's survival time is drastically decreased when immersed in cold water, several devices have been disclosed to insulate the body to prevent heat loss. These devices include so-called survival suits, which are very similar to the neoprene suits worn by skin divers. There have also been many devices disclosed to aid in the location of a person who has been lost overboard. These devices include passive structures such as brightly colored apparel and signal mirrors for reflecting sunlight, as well as active devices, such as electric lights and portable radio transmitters.
Although the aforementioned survival devices can be quite effective, they are bulky, expensive, and serve no purpose other than safety. Because of these drawbacks, few sailors wear the aforementioned survival devices during their normal day-to-day duties. Since many man-overboard accidents have happened inadvertently during non-emergency work situations, persons such as the aforementioned sailors have been denied the benefit of survival equipment.
Marine radar is a highly effective tool in locating and tracking the position of targets having suitable microwave-reflective qualities. It has long been known that a so-called corner reflector, comprising three perpendicular intersecting planes of microwave-reflective material, such as metal, provides an excellent radar target. The geometry of the corner reflector causes any incident ray to be reflected in an exactly parallel direction. Corner reflectors have found wide use on buoys, boats, and other objects where safety depends on their effective detection by radar.
The canteens and various marine survival devices of the prior art are all distinguishable from the instant invention in that none discloses or even suggests the unique structure of a microwave-transparent canteen having internal microwave-reflective baffles which aid in maintaining its dynamic stability and which are configured so as to provide a highly efficient radar target.